This paper presents a design for a cutting-edge English program in which elementary school learners of English as a foreign language in Taiwan had lively interactions with a teaching assistant robot. Three dimensions involved in the design included (1) a pleasant and interactive classroom environment as the learning context, (2) a teaching assistant robot designed and built by the researchers as instructional technology (instructional tool/medium), and (3) the need for improved motivation and learning outcomes and positive learning experiences of the students as the core research problem. This Human-Robot Interaction (HRI) led to better pedagogical effects on learning and teaching by (1) employing a vivid, enjoyable teaching approach; (2) adopting practical, interesting learning materials; and (3) creating a natural, enjoyable learning context. Both quantitative and qualitative findings of this study indicate that the students' English learning experiences were enhanced, as were their motivation and learning outcomes as a result of this HRI. This paper, instead of merely suggesting design criteria for robots, provides a set of instructional design guidelines that other researchers can follow to create an innovative and enjoyable English classroom that employs an interactive robot as an assistant for enhancing English acquisition while simultaneously reducing the pressure and teaching load of the English instructors.